Blackjack

Provably fair

Verify fairness

The session's seed decides every card. Its hash was committed before the first hand; the seed is revealed when the session ends. Each round's cards come from HMAC-SHA256 keyed by the seed over the round's number and the bettor's own seed.

Seed hash

11836fd5b5143955044eb4a90e011aaf3b97e69501e6df89a2a4b6ff8fe327c9

Seed

91da86fe7aecc5970c2dc4f6c9852b88d3336dff9748d7efce9c806aa3f3a4ab SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

a78e5a3678df2b42ab62808e77e2f4b9

Commitment

Batch 50,676, Merkle root 8b0f3fd0f943846f0eda8a9af0d1821b2f7e33787e136507bfc88d627b901ad5. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 71cce05c7b85d8ac40a9c02d6a4cb24082f0a6db3b27ca5f7aacb7b641957d3d
2. 6ce3ea6e72889a667200f99707b0d223f435d5799209cfedaec9161cf4656d4d

Checked: the seed hash proves into the root.

To check it yourself, take the session's proof:

1. Hash the seed as above and compare it with the seed hash; prove the seed hash into the root with the Merkle path (keccak256, as for every match).
2. For each round: round seed = HMAC-SHA256(key = seed, "degen.house.round.v1" ‖ 0x00 ‖ u64be(length of the bettor's seed) ‖ bettor's seed ‖ u64be(round)).
3. Key ChaCha20 (RFC 8439, zero nonce) with the round seed and read little-endian 64-bit words; a card is the next word below 2⁶⁴ − 1 − ((2⁶⁴ − 1) mod 52), modulo 52.
4. Replay the round's actions with the game's rules: the cards and the payout must match.

The replay plays every hand rebuilt this way on the server from the same data, and marks any that does not rebuild as recorded.